Ultrasonic Transducer and Horn Used in Oxidative Desulfurization of Fossil Fuels

ABSTRACT

Devices and improved methods are provided for operation of ultrasonic transducers and horns.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No. 60/948,168, filed Jul. 5, 2007, which is incorporated herein by reference in its entirety.

BACKGROUND

A variety of legal, social and commercial efforts have taken place over the past 50 years and more, aimed at the removal of sulfides from fossil fuels. In the U.S., the Clean Air Act of 1964 and its evolution of amendments has been a major driving force in these efforts. Despite the benefits of low sulfide fossil fuels, the associated costs, undesirable changes to conventional methods of manufacture, which may impose unreliability and inefficiency of attempted improvements, have been a hindrance to progress and to obtaining the benefits from desulfurization of sulfur fuel. Some of this unreliability and inefficiency has been related to the control of temperature, pressure, corrosion and power in the chamber of the ultrasonic transducer, which in turn affects the performance of an ultrasonic horn for use in oxidative desulfurization of fossil fuels.

There remains a need to efficient and effective devices and methods for desulfurization. The present invention provides apparatus and methods for desulfurization using an ultrasonic horn.

SUMMARY OF THE INVENTION

In one aspect of the invention, an apparatus comprising a chiller-heater exchanger for circulating a dielectric coolant through a ultrasonic transducer and horn chamber (e.g., Cooling chamber for the magnetostrictive or transducer portion of the ultrasonic device). In various embodiments, the dielectric coolant is a fluorocarbon. In other embodiments, the coolant is an HFE.

In some embodiments, the coolant is circulated through an ultrasonic chamber and horn (e.g., Below transducer, magnetostructure side of the device) which is in fluid communication (e.g., input and output) to the exchanger. Such an exchanger can heat/cool the coolant as desired. The fluorocarbon coolant provides an improved method to regulate temperature, pressure and corrosion of the ultrasonic horn. In some embodiments, the coolant reduces, reduces significantly or eliminates corrosion.

In further embodiments, given the anticorrosive properties of the coolant, the ultrasonic horn is not required to comprise a protective or insulating layer in the form of a laminate or covering as is conventional. In additional embodiments, increased control of waveform frequency can be achieved through improved temperature regulation, as well as obviating the need for insulation or amount of insulation coating a horn. For example, the ultrasonic horn is capable of more effectively and efficiently dissipating heat to the coolant. Therefore, in some embodiments, an ultrasonic horn is able to function longer or at a more stable frequency; and more durably as it is resistant to corrosion.

A method of desulfurization of a material comprising sulfur comprising administering ultrasonic energy to the material as at passes through continuous flow through the ultrasonic energy.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which:

FIG. 1 illustrates a chiller-heater exchange device of the invention (100: chiller-heater exchanger; 101: channel flowing to ultrasonic horn chamber; 102: intake port to chamber; 103: cooling jacket assembly; 104: outflow port; 105: channel for circulating coolant back to exchanger; 106: ultrasonic horn with magnetostrictive laminates and windings; 107: flange/adaptor for mating with reaction chamber).

DETAILED DESCRIPTION OF THE INVENTION

In general, products and processes of the invention are directed to an effective and improved means for operating an ultrasonic transducer. Aspects of the invention are directed to controlling temperature, pressure, power, dielectric properties (e.g., safety benefits and enhancing heat transfer efficiency), and corrosion (e.g., oxidative) of the chamber environment surrounding an ultrasonic transducer.

Methods and Apparatuses

In various embodiments, an methods and apparatus of the invention provide temperature control or enhanced temperature control, control of pressure, elimination, abatement or reduction of corrosion and enhanced power of the ultrasonic transducer (including in the ultrasonic transducer chamber and the parts it contains).

As illustrated in FIG. 1, in one embodiment, an apparatus of the invention is comprised of (1) a chiller-heater exchange device, which outputs (2) coolant to the ultrasonic transducer chamber and subsequently recycles the same fluid that has been heated in the (4) chamber via a return (3) connection. In a further embodiment, the coolant The present application describes a hydrofluoroether compound and the use of the hydrofluoroether compound as a heat-transfer fluid. The hydrofluoroether compound may be used to heat, cool, and/or maintain the temperature of the device at a select temperature. The hydrofluoroether compound is inert, non-flammable, and environmentally acceptable. Additionally, the hydrofluoroether compound of the present invention exhibits low viscosity throughout the liquid range, and has good heat transfer properties over a wide temperature range. In various embodiments, an ultrasonic transducer cooled with a coolant described above is utilized in a method of desulfurizing fossil fuels.

In one embodiment, a ultrasonic transducer and horn chamber wherein the ultrasonic horn is encased in a coolant jacket.

In one embodiment, the apparatus comprises a heater-chiller exchanger and fluorocarbon fluid. The apparatus provides increased longevity (e.g., life-span), improved reliability and performance of the transducer and horn.

In one embodiment, the ultrasonic device of the invention, which is cooled with a coolant as described herein, is utilized in a method of desulfurizing fossil fuels or producing desulfurized fossil fuels.

d. Liquid Fossil Fuels

The term “liquid fossil fuels” is used herein to denote any carbonaceous liquid that is derived from petroleum, coal, or any other naturally occurring material and that is used to generate energy for any kind of use, including industrial uses, agricultural uses, commercial uses, governmental uses, and consumer uses. Included among these fuels are automotive fuels such as gasoline, diesel fuel, jet fuel, and rocket fuel, as well as petroleum residuum-based fuel oils including bunker fuels and residual fuels. Bunker fuels are heavy residual oils used as fuel by ships and industry and in large-scale heating installations. No. 6 fuel oil, which is also known as “Bunker C” fuel oil, is used in oil-fired power plants as the major fuel and is also used as a main propulsion fuel in deep draft vessels in the shipping industry. No. 4 fuel oil and No. 5 fuel oil are used to heat large buildings such as schools, apartment buildings, and office buildings, and large stationary marine engines. The heaviest fuel oil is the vacuum residuum from the fractional distillation, commonly referred to as “vacuum resid,” with a boiling point of 565° C. and above, which is used as asphalt and coker feed. The present invention is useful in reducing the sulfur content of any of these fuels and fuel oils. In certain embodiments of the invention, the liquid fossil fuel is diesel fuel, either straight-run diesel fuel, rack diesel fuel (diesel fuel that is commercially available to consumers at gasoline stations), and blends of straight-run diesel and light cycle oil in volume ratios ranging from 50:50 to 90:10 (straight-run:light cycle oil). In further embodiments, the fossil fuel is crude fuel, including sour crude, sweet crude or light sweet crude.

In yet other embodiments, apparatus and methods of the invention are applied to any sulfur containing, low sulfur or ultra low sulfur containing fuels. Such

b. Chiller-Heater

In one embodiment, the chiller-heater device is capable of delivering chilled fluid that is about −20 C to an ultrasonic transducer chamber, and is also capable of processing return fluid of about 120 C or less for subsequent re-delivery to said chamber. In another embodiment, the chiller-heater device is capable of delivering chilled fluid that is about −150, −125, −124, −123, −122, −121, −120, −119, −118, −117, −116, −115, −114, −113, −112, −111, −110, −100, −99, −98, −97, −96, 95, −94, −93, −92, −91, −90, −89, −88, −87, −86, −85, −84, −83, −82, −81, −80, −79, −78, −77, −76, −75, −74, −73, −72, −71, −70, −69, −68, −67, −66, −65, −64, −63, −62, −61, −60, −59, −58, −57, −56, −55, −54, −53, −52, −51, −50, −45, −40, −35, −30, −25, −20, −15, −10, −5, 0, 5 or 10 C; and is also capable of processing return fluid of about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 100, 110, 125, 130, 135, 140, 145, 150, 155, 160, 170, 180, 190, 200, 210, 215, 220, 225, 230, 235, 240, 250, 260 or 275 C. Therefore, in various such embodiments, the coolant is capable of reaching temperatures as disclosed herein. Such exchangers are commercially available and readily adaptable to the devices and methods of the invention. Examples of such exchangers are provided in U.S. Pat. Nos. 7,255,160; 7,257,958; 7,059,137; 7,246,940; and 4,301,968.

d. Coolant

In one embodiment, the coolant fluid is a fluorocarbon or hydrofluoroether compound with boiling point less than 145 C and pour point greater than −50 C at STP (standard temperature and pressure at 1 atmosphere), which prevent corrosion, are strong dielectrics and are flexible enough in boiling and pour points to enable the changes in temperature required to enhance the overall process. Thus, the apparatus of the invention comprises a heat-transfer fluid that preferably performs well at both low and high temperatures (i.e., preferably has good heat transfer properties over a wide temperature range), is inert (i.e., is non-flammable, low in toxicity, non-chemically reactive), has high dielectric strength, has a low environmental impact, and has predictable heat-transfer properties over the entire operating temperature range. In various embodiments, the coolant obviates limitations associated with conventional coolant fluids, e.g., deionized water, water/glycol mixtures, such as corrosion. Furthermore, devices and systems of the invention comprise a coolant that provides a substantially inert environment, thus preventing corrosion associated with conventional coolants.

Therefore, the coolant utilized to cool the ultrasonic transducer is earth friendly or green and has a boiling point less than about 145° C. and pour point greater than −50 C at STP. For example, the coolant is non-ozone depleting, is not a volatile organic compound (VOC) and is approved without restrictions under the US EPA's Significant New Alternatives Program (SNAP). For example, in various embodiments, a coolant is an HFE having a has a short atmospheric lifetime and low global warming potential (GWP), a relatively higher boiling point (e.g., compared to water) which reduces evaporative losses and its lower density which reduces the amount of fluid to fill a ultrasonic transducer machine. Furthermore, the corrosive properties associated with other coolants (e.g., water) is obviated by utilizing HFE. A further examples includes HFEs disclosed in U.S. Pat. No. 7,055,579, which is incorporated herein in its entirety. Furthermore, any safety issues with having high voltage electricity running near or with an electrical conducting coolant (e.g., water) is obviated.

In addition, a wide liquid range (−138° C. to 76° C.) makes HFE-7200 well-suited to thermal management applications for ultrasonic transducers of the invention. In addition, HFE-7200 fluid has a very low global warming potential (GWP) and offers reduced greenhouse gas emissions when compared to PFCs—without sacrificing performance.

Another advantage to utilizing the fluorocarbons as a liquid coolant in the apparatuses of the invention is their dielectric characteristics. A dielectric is an electrical insulator in that it is highly resistant to the flow of an electric current. As such, coolants disclosed herein further reduce or eliminate corrosion that is otherwise observed in prior art ultrasonic transducer and horns.

d. Ultrasonic Transducer

Ultrasonic devices of the invention are configured to be directly immersed in the cooling liquids disclosed herein. In one embodiment, an ultrasonic transducer and horn chamber is configured to have an input and output channel for the liquid coolant which channels are operatively linked to a chiller-heater exchanger.

Exemplary ultrasound used in accordance with this invention can produce soundlike waves whose frequency is above the range of normal human hearing, i.e., above 20 kHz (20,000 cycles per second). Ultrasonic energy with frequencies as high as 10 gigahertz (10,000,000,000 cycles per second) has been generated, but for the purposes of this invention, useful results will be achieved with frequencies within the range of from about 15 kHz to about 200 kHz, and preferably within the range of from about 15 kHz to about 50 kHz. Ultrasonic waves can be generated from mechanical, electrical, electromagnetic, or thermal energy sources. The intensity of the sonic energy may also vary widely. For the purposes of this invention, best results will generally be achieved with an intensity ranging from about 30 watts/cm² to about 300 watts/cm², or preferably from about 50 watts/cm² to about 100 watts/cm². The typical electromagnetic source is a magnetostrictive transducer 106 which converts magnetic energy into ultrasonic energy by applying a strong alternating magnetic field to certain metals, alloys and ferrites. The transducer is cooled by the coolant circulated via the chiller-heater exchanger 100. Furthermore, the transducer 106 can be fitted with an adaptor, such as a flange 107 so as to couple the device to a reaction chamber (not shown).

In one embodiment, the coolant is circulated through a cooling jacket assembly 103. Thus, in one example, the flange (107) ‘mates’ with the reactor chamber flange (which brings the sulfur containing compound or other fluid to be treated past the ultrasonic device of the invention.

In other embodiments, the transducer/horn is in direct contact with the coolant, where the transducer/horn is coupled to a cooling chamber with in/out ports for circulating the coolant. For example, the transducer can function just as well where in direct contact with the coolant (e.g., HFE).

Another typical electrical source is a piezoelectric transducer, which uses natural or synthetic single crystals (such as quartz) or ceramics (such as barium titanate or lead zirconate) and applies an alternating electrical voltage across opposite faces of the crystal or ceramic to cause an alternating expansion and contraction of crystal or ceramic at the impressed frequency.

A transducer can be powered by any oscillating voltage. The oscillations can be a continuous waveform oscillation such as sinusoidal wave or a series of pulses such as rectangular waveform pulses. By “rectangular waveform” is meant a direct current voltage that alternates through stepwise voltage changes between a constant positive value and a baseline value. Rectangular waveforms that are preferred in the practice of this invention are those in which the baseline is a negative voltage rather than a zero voltage, and preferably those in which the alternating positive and negative voltages are of the same magnitude. In some embodiments, the voltage is from about 140 volts to about 400 volts, and preferably about 220 volts single-phase, and the preferred wattage is from about 1 kilowatt to about 17 kilowatts. The frequency of the voltage oscillation will be selected to achieve the desired ultrasound frequency. For example, the frequencies are in the range of about 10 to about 50 megahertz, with a range of about 15 to about 30 megahertz preferred. Any transducer that would benefit from enhanced control of temperature, pressure or the prevention of corrosion could be utilized in the present systems and methods.

Ultrasound has wide applications in such areas as cleaning for the electronics, automotive, aircraft, and precision instruments industries, flow metering for closed systems such as coolants in nuclear power plants or for blood flow in the vascular system, materials testing, machining, soldering and welding, electronics, agriculture, oceanography, and medical imaging. The various methods of producing and applying ultrasonic energy, and commercial suppliers of ultrasound equipment, are well known among those skilled in ultrasound technology and such as disclosed in U.S. Pat. Nos. 6,402,939; 6,500,219; 6,652,992; and U.S. Patent Application Publication Nos. 2006/0260405, 2006/0196915 and 2005/0274600, 2003/0051988, and 2004/0079680.

The ultrasonic transducer and ultrasonic horn 106 in particular can be of any conventional shape and size that may be known in the prior art for ultrasonic horns. The horn may for example be cylindrical, preferably of circular cross section as indicated above, and suitable lengths may range from about 4 cm to about 100 cm (including half wave or full wave horns), depending on the reactor size, or from about 10 cm to about 50 cm, with a diameter of from about 3 cm to about 30 cm, or from about 5 cm to about 15 cm. For example, a block on which an ultrasonic horn is disposed, can serve as both a mechanical connection that transmits the ultrasound vibrations from the transducer to the horn and an amplifier can likewise vary in its dimensions. For example, a suitable length range is about 5 cm to about 100 cm, and most preferably from about 10 cm to about 50 cm, with its widest diameter ranging from about 3 cm to about 30 cm, and preferably from about 5 cm to about 15 cm. The horn is adaptable to a reaction chamber through various fittings conventional in the art.

In various embodiments, the ultrasonic chamber can provide continuous flow of the material to be desulfurized. For example, the material (e.g., crude resin or diesel fuel) to be treated follows a flow path that sweeps across a reaction chamber configured to couple to an ultrasonic horn 106, with a continuous, constant flow and little or no dead volume. The reaction chamber can be of any size, geometry or dimensions, so long as it is configured to receive the ultrasonic horn.

Generally, the ultrasound generates heat, and with certain fossil fuels it is preferable to remove some of the generated heat to maintain control over the reaction. However, with the present invention, the given the apparatus is configured to provide a coolant that is anti-corrosive, there is no need to provide an ultrasonic horn with a protective laminate, layer or adhesion. Therefore, in various embodiments apparatus of the invention provide a coolant to regulate the temperature in the ultrasonic chamber while concomitantly reducing or eliminating corrosion in the ultrasonic chamber. In other embodiments, the ultrasonic chamber is itself encased in a cooling jacket which provides circulation of the coolant disclosed herein to and from the ultrasonic chamber from the chiller-heater exchanger.

As indicated in FIG. 1, the ultrasonic transducer and horn chamber is directly in contact with the coolants disclosed herein. Furthermore, as the coolant is anti-corrosive and no protective layer is required for the horn, heat is dissipated from the horn more efficiently thus allowing prolonged and more durable operation (e.g., no overheating). For example, transducers can comprise a protective layer of a laminate material or silicone such as disclosed in U.S. Pat. No. 7,033,673. Apparatus of the invention can be configured to not contain such protective coatings owing to the anticorrosive properties of the coolant discloses herein.

When cooling is achieved by immersing the ultrasound chamber in a coolant bath or circulating coolant, the coolant may be at a temperature of about 50° C. or less, about −50° C. or less, or about −120° C. Other operating conditions in the ultrasound chamber can vary as well, depending on the material being treated and the throughput rate. The pH of the emulsion, for example, may range from as low as 1 to as high as 10, although best results are generally achieved within a pH range of 2 to 7. The pressure of the emulsion as it is exposed to ultrasound can likewise vary, ranging from subatmospheric (as low as about 0.2 psia to about 5 psia or 0.34 atmosphere) to as high as 3,000 psia (214 atmospheres). In some embodiments, the pressure is less than about 400 psia (27 atmospheres), or less than about 50 psia (3.4 atmospheres). In further embodiments, the pressure is from about 1 psia atmospheric pressure to about 50 psia. For example, the pressure may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50 psia.

An advantage of the present invention is that the process and equipment can treat fossil fuels, petroleum fractions, with prolonged operation of the ultrasonic horn. The dielectric coolant provides enhanced temperature regulation and based on the anticorrosive properties, the horn is not required to be coated with any protective layer. As such, the horn more efficiently dissipates heat and is more effectively cooled thus allowing prolonged operation. As such a greater volume of an emulsion (e.g., fuel emulsion) is able to be processed over a given period of time. For example, in various embodiments, throughput rates of the oil phase are from about 5 to about 500 gallons (U.S.) per minute (about 0.3 to about 30 L/sec), and most preferred are from about 8 to about 160 gallons (U.S.) per minute (about 0.5 to about 10 L/sec).

While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby. 

1. An apparatus configured to provide enhanced regulation of temperature and corrosion comprising a chiller-heater exchanger component, in liquid communication with an ultrasonic transducer chamber, wherein said chamber is cooled by a dielectric coolant.
 2. The apparatus of claim 1, wherein said liquid communication comprises a channel for receiving coolant from said chamber and a channel for delivering coolant to said chamber.
 3. The apparatus of claim 1, wherein said ultrasonic transducer comprises a horn that is not coated by a protective compound.
 4. The apparatus of claim 1, wherein said coolant is a fluorocarbon.
 5. The apparatus of claim 1, wherein said coolant is a hydrofluoroether.
 6. The apparatus of claim 1, wherein said coolant has a boiling point less than 145° C. and pour point greater than −50° C. at STP.
 7. The apparatus of claim 1, wherein said coolant is in direct or indirect contact with said horn.
 8. A method for emitting ultrasonic energy through a fuel material comprising, conducting an ultrasonic horn to emit ultrasonic waves through said material, and cooling said ultrasonic horn via a heat-chiller exchanger which circulates a dielectric coolant
 9. The method of claim 8, wherein said fuel material is sulfur containing fuel.
 10. The method of claim 8, wherein said coolant is directly in contact with said horn.
 11. The method of claim 8, wherein said coolant is comprised in a cooling jacket which is in contact with said horn.
 12. The method of claim 8, wherein said coolant reduces or prevents corrosion of said horn.
 13. The method of claim 8, wherein said horn is not coated by a protective or insulating compound.
 14. The method of claim 8, wherein said coolant is a hydrofluoroether.
 15. The method of claim 8, wherein said coolant is a fluorocarbon.
 16. The method of claim 8, wherein said conducting results in oxidative desulfurization of said fuel.
 17. The method of claim 8, wherein said coolant has a boiling point less than 145° C. and pour point greater than −50° C. at STP. 